The present invention relates in general to the field of medical biopsy instruments, and more particularly, to such instruments for use in fine needle biopsy of human or animal tissue for medical diagnostics and the like.
Biopsy instruments are often used to obtain tissue samples for microscopic examination to test for malignancy or other diseases and abnormalities. Generally, biopsies may be guided by either stereotactic means, CAT scan or ultrasound means. Image-guided biopsy procedures are particularly useful for non-surgical diagnosis of benign and malignant masses. The biopsy itself may be either a core biopsy or a fine needle aspiration biopsy. For example, an instrument for performing percutaneous biopsy procedures and collection of soft tissue is disclosed in Ritchant, et al., U.S. Pat. No. 5,649,547.
Other currently used biopsy instruments and methods include those disclosed in Siczek, et al., U.S. Pat. No. 5,415,169 and Assa, U.S. Pat. No. 5,240,011, Siczek, et al. and Assa each disclose a motorized biopsy needle positioner employed in a mammographic needle biopsy system for receiving coordinate information representative of an identified point of interest within the patient""s captive breast under examination and automatically positioning a biopsy needle in accordance with the coordinate information to permit insertion of the biopsy needle to the identified point of interest.
Additionally, Clement, et al., U.S. Pat. No. 5,368,045 discloses a handheld biopsy needle instrument employing combined stylets and cannulas capable of taking multiple specimens while the other hand is free to manipulate an ultrasound probe. The stylet and cannulas are spring loaded, which upon firing, will penetrate the tissue for obtaining a biopsy specimen. A similar biopsy instrument having a plurality of stylets and cannulas which can be controlled independently for capturing a plurality of discreet specimens at a controlled depth is disclosed in Chin, et al., U.S. Pat. No. 5,415,182. See also Akerfeldt, U.S. Pat. No. 4,944,308.
Fine needle aspiration biopsy is often performed on a potentially malignant mass for confirmation of diagnosis prior to surgery, on more than one mass where multi-focal or multi-centric malignant disease is suspected, on a suspected benign lesion such as a fibroadenoma, where there is ambivalence about follow-up versus excision, or on an ultrasound imaged structure with features unlike a simple cyst. Among the benefits of fine needle aspiration when compared with other biopsy procedures are that it is less invasive, requires no incision, causes minimal discomfort, takes less time and costs considerably less. A discussion of fine needle aspiration is disclosed in the article Fine Needle Aspiration, Kathleen M. Harris, M. D., FACR, pp. 101-105.
Suction and capillary methods of aspiration have been successful on the breast. For suction aspiration, a syringe in a resting position is attached to a sampling needle. Suction is created by pulling the plunger of the syringe. In the capillary method, a syringe is not used and suction is not applied. With both methods, up to the present time the sampling needle is manually moved back and forth rapidly by the physician within the area to be studied. The needle is further angled in multiple directions to sample a cone-shaped area within the area to be studied. In the suction method, the suction should be maintained until material is visible in the plastic needle hub, or for a minimum of twenty up-and-down motions in varying directions. This method is described further in Interventional Breast Procedures, edited by D. David Dershaw, pp. 91, 94 and 95. A similar technique is described in General Ultrasound, Ed., Carol A. Mittelstaedt, M. D., pg. 18. The technique is also described in Interventional Breast Ultrasonography, Ellen B. Mendelson, M. D., pp. 57-76. Another similar technique is that discussed in Thyroid and Parathyroid, pg. 107.
Until now, and as described in the foregoing references, fine needle aspiration biopsies have been performed manually. Such a procedure involves manually thrusting a needle alone or a needle attached to a syringe, with or without suction. The procedure is generally random in that the depth of the thrusts, number of thrusts, the area covered and the force used are done in a very haphazard way. For example, one thrust could be 5 millimeters, while another could be 2 millimeters and so forth.
A significant limitation with random depth is that when a lesion is very small in diameter, there are occasions where none or a few of the thrusts obtain the necessary tissue sample. One of the thrusts may be directed to a lesion, but may bypass the lesion completely as a result of a lack of consistent direction of the thrusts. Random depth results in a significant amount of fine needle aspiration biopsies retrieving an insufficient amount of tissue with which to do an appropriate diagnostic evaluation. If the number of thrusts is limited, this compounds the problem further and increases the chances of missing the lesion.
Another limitation of the prior method is lack of significant thrusting energy. The force behind the thrust may be variable, and many may be insufficient enough to pierce the outer margins of certain lesions, especially fibroadenomas. The needle can potentially bounce off the fibroadenoma or push it aside rather than pierce the outer margin and obtain the necessary tissue.
Many fibroadenomas are currently surgically excised without any attempt to perform a fine needle biopsy. The cost of excisional biopsies are multiple times the cost of a fine needle aspiration biopsy. Significant medical financial resources could be saved by performing fine needle aspiration biopsies instead of excisional biopsies. Providing an improved method and an automated biopsy instrument for performing fine needle aspiration biopsies would reduce the need for excisional biopsies together with their inherent risks.
There is disclosed in Dejter, Jr., et al., U.S. Pat. Nos. 5,060,658 and 4,989,614 a medical instrument for fine needle aspiration biopsies of the prostate only. The biopsy instrument includes a needle having an opening which can be occluded by a stylet during both the penetration and withdrawal stage of an aspiration cycle during the biopsy procedure. After penetration of the target tissue, the needle is reciprocated a predetermined number of times as determined by the desired cytological sample yield. During the reciprocating procedure, the needle opening remains unoccluded by withdrawal of the stylet. Tissue sample is collected in a syringe under vacuum. After sufficient tissue sample has been collected, the stylet is returned to its forward position, thereby occluding the needle opening prior to withdrawal of the needle from the patient. The biopsy instrument is opened in order to remove the syringe containing the collected tissue sample for cytological analysis.
Naslund, U.S. Pat. No. 4,605,011 discloses a biopsy instrument for taking samples of cells of small tumors using fine needle puncturing techniques. The biopsy instrument includes a hand grip having a syringe provided with a removable cannula. The cannula is connected to a motor which is operative for driving the cannula in an oscillating, recipricatory motion. The motor is constructed as an electromagnet having pole elements, which when energized, cause reciprocal motion of a pole element which is coupled to the cannula. The cannula is connected to a container which is placed under vacuum for drawing a tissue sample from the cannula during the biopsy procedure. This instrument is not used without suction.
Patipa, et al., U.S. Pat. No. 4,644,952 discloses a surgical operating instrument provided with a needle which can be reciprocated by means of a cam and cam follower arrangement. The needle is attached to one end of a shaft, the other end supporting a laterally extending cam follower. The cam follower is captured interiorly within a cam between two opposing cam surfaces. The cam is rotated by a motor thereby effecting reciprocal motion of the needle. There is no stated use for the instrument disclosed in Patipa, et al.
The instruments disclosed in Dejter, Jr., et al., Naslund and Patipa, et al., although effecting reciprocal motion of the needle or cannula, have designs which provide disadvantages in fine needle biopsy procedures. For example, in certain cases the disclosed designs are complicated and therefore expensive to manufacture, do not provide accurate control of the reciprocal motion and thrust force required of fine needle biopsy procedures, are bulky or cumbersome in size making the instrument difficult to handle during the biopsy procedure, require the use of a stylet, or are not suitable for vacuum collection of a tissue sample. Similar disadvantages are known from a medical instrument which effects reciprocal motion of a needle by a rotating cam and spring arrangement. The cam is operative for advancing the needle in a forward direction, the return motion being effected by a compression spring.
There is accordingly the need for improvements in fine needle biopsy instruments which provide reciprocal and/or rotational motion of the needle to collect tissue samples for medical diagnostics in an accurate and efficient manner, while being suitable for use in various environments such as hospitals and the like.
The present invention broadly addresses the need for improved quality and completeness of technique, as well as an improved instrument for obtaining tissue samples through fine needle biopsy.
The present invention involves the use of fine needle biopsy techniques with a biopsy needle instrument that may be programmed to provide a predetermined depth and number of thrusts, a predetermined thrust cycle, a predetermined pattern and/or area to be covered, and a predetermined force of thrust. By manually changing slightly the angle of the device with the needle, multiple areas of the tumor can be sampled in a very short period of time. The needle or syringe is attached to a small handheld device, which can be driven by a small electric motor or hydraulic fluid, e.g., compressed air and the like. The needle can move in a xe2x80x9cjackhammerxe2x80x9d type fashion to implement the programmed settings for depth, number, cycles and force of thrusts. The force behind each thrust could be constant and of sufficient magnitude to pierce the outer margin of a small lesion such as a fibroadenoma rather than pushing them aside because of insufficient force. The device can be used with or without suction for aspiration of the tissue sample. Since all the functions of the instrument can be predetermined and preprogrammed, the physician can start the procedure, focus on the ultrasound monitor and then position the needle in juxtaposition to the lesion. The invention also incorporates a safety mechanism or xe2x80x9cdeadman switchxe2x80x9d to prevent accidental initiation of the reciprocal action of the needle prior to the actual biopsy.
The fine needle aspiration biopsy instrument in accordance with the present invention generally includes a powered handpiece, a biopsy needle to be inserted into the handpiece, an internal programmable controller or remote programmable computer for controlling the instrument, a power source for operation of the instrument and a suction source. As will be understood from a further description of the present invention, the suction connection is an optional feature.
The instrument to which the biopsy needle is attached is operative to provide at least one, and preferably two motions to the biopsy needle. Specifically, the instrument incorporates a jack-hammer type motion that causes a reciprocal thrusting motion of the biopsy needle into the tissue to be biopsied, and optionally, a rotary motion of the biopsy needle which will produce a cutting effect.
The power source is operative for providing the necessary power for operating the instrument to affect the reciprocal and/or rotary type motion of the biopsy needle by means of, for example, an electric or pneumatic operated motor for operation of a reciprocating/rotating assembly as disclosed pursuant to the present invention. In addition to the thrusting or reciprocal motion, the biopsy needle may also be rotated or manipulated about an orbital pattern as opposed to rotation along its longitudinal axis, which is also contemplated pursuant to the present invention. Further in this regard, a suitable cam assembly or other such mechanism can be inserted into the handpiece to affect orbital rotation of the biopsy needle in a predetermined pattern, for example, oval, circular, random, zig-zag, rectangular and the like. In use, the thrusting action of the biopsy needle will orbit such that the pattern of specimens taken of the tissue sample will correspond to the predetermined pattern defined by the cam assembly or other such mechanism in the instrument. It is therefore possible for the instrument to sample the tissue at a plurality of random or predetermined locations to ensure that the area from which specimens are to be taken is adequately sampled.
The programmable controller or computer may be set according to the desired parameters either before or after insertion of the needle into the patient. When the physician is ready for the sample to be taken, he or she may activate the instrument by turning a switch that controls the power source, e.g., electricity or hydraulic source. As the sample is being taken, the physician is free to focus on the ultrasound monitor which will demonstrate the lesion together with the needle within it. By focusing on the monitor, this ensures that the tissue extracted is from the lesion itself and not from the surrounding tissues.
A programmable device for use in association with the instrument permits programming of the depth of thrusts, the number of thrusts per unit of time, the area or pattern of thrusts, the force of the thrusts, as well as other variable options to specifically select desired parameters. A programmable device may be provided within the handpiece itself or may be remote therefrom such as using a programmable computer.
By way of one illustrative example, the biopsy needle used for fine needle aspiration may range from 20 gauge to 25 gauge, having a 4.0 mm stroke length, a zig-zag area pattern, e.g., 2-6 mm travel between thrusts and 10-20 strokes per second for 5 seconds. The biopsy needle may be connected to the handpiece using any suitable connector which is well known in the medical field and the aforementioned cited prior art.
It can be appreciated from the foregoing description of the biopsy needle instrument in accordance with the present invention, that the physician can program the instrument to accommodate any specific tissue or lesion to be biopsied with a number of variable parameters to ensure that sufficient samples of tissue for biopsy are obtained. Once the specimen has been obtained, with or without suction, into the biopsy needle, the specimen can be extracted into a jar of preservative fluid or onto a slide for analysis.
In accordance with one embodiment of the present invention there is described a medical instrument comprising a housing having an opening at one end thereof; a first shaft within the housing for reciprocal motion, the first shaft having a front section and a rear section, the front section of the shaft extending adjacent the opening in the housing; a cam assembly within the housing, the cam assembly comprising first and second cam followers arranged in spaced apart relationship on the first shaft, a cam arranged between the first and second cam followers mounted on a rotatable second shaft, the cam having outwardly facing first and second cam profiles respectively engaging an opposing one of the first and second cam followers, whereby the cam assembly upon rotation of the cam converting rotating motion of the second shaft to reciprocal motion of the first shaft.
In accordance with another embodiment of the present invention there is described a medical instrument comprising a housing having an opening at one end thereof; a reciprocating shaft within the housing, the reciprocating shaft having a front section and a rear section, the front section of the shaft extending outwardly through the opening; a cam assembly within the housing operatively coupled to the reciprocating shaft, the cam assembly comprising a cam having first and second spaced apart outwardly facing cam profiles, a first cam follower on one side of the cam in engagement with the first cam profile, and a second cam follower on the other side of the cam in engagement with the second cam profile; and a motor operatively coupled to the cam for rotational movement of the cam, whereby the engagement of the first and second cam profiles with the first and second cam followers during rotation of the cam causes reciprocal movement of the reciprocating shaft.
In accordance with another embodiment of the present invention there is described a medical instrument comprising a housing having an opening at one end thereof; a reciprocating shaft along a first axis within the housing, the reciprocating shaft having a front section and a rear section, the front section of the shaft extending outwardly through the opening; a cam assembly within the housing comprising a cam having first and second spaced apart cam profiles, a first cam follower on one side of the cam in engagement with the first cam profile, and a second cam follower on the other side of the cam in engagement with the second cam profile; and a motor on a second axis within the housing operatively coupled to the cam for rotational movement of the cam, the second axis offset from the first axis, whereby rotation of the cam causes reciprocal movement of the reciprocating shaft.
In accordance with another embodiment of the present invention there is described a medical instrument comprising a housing having an opening at one end thereof; a shaft within the housing for reciprocal motion, the shaft having a front section and a rear section, the front section of the shaft extending outwardly through the opening of the housing; a motor within the housing; and a cam assembly within the housing comprising a cam operationally coupled to the motor for rotational movement of the cam, the cam having a track and a cam follower fixed to the housing and received within the track; whereby receipt of the cam within the track during rotation of the cam by the motor causes reciprocal movement of the shaft.